The 2.5km was on 87 SSB.  On 27 we used NBFM (much shorter range).

John F5VLF

*********** REPLY SEPARATOR  ***********

On 22/02/2010 at 19:54 Roger Lapthorn wrote:

>Presumably the 2.5kms on 87 or 27kHz was using USB John, or at least in
>USB
>bandwidths? Assuming a mode like QRSS30 or QRSS60, this would imply that
>considerably further DX would be possible, even allowing for an inverse
>cube
>attenuation rate.
>
>I wonder if anyone has any lists of DX achieved using induction mode
>communications?
>
>73s
>Roger G3XBM
>
>On 22 February 2010 17:51, John RABSON <[email protected]> wrote:
>
>> If I recall correctly, G0AKN (now SK) tried audio frequencies as well as
>73
>> and 136 kHz.  G8DSU, who monitors this list, may have more information. 
>An
>> article by G0AKN on this subject appeared in the Jan-Feb.1999  issue of
>the
>> AMRAD newsletter.  More information may be found by searching online for
>> G0AKN.
>>
>> Most cave radio work takes place on 87kHz USB although we have sometimes
>> used frequencies as low as 27kHz.  The maximum range we have achieved
>with a
>> 4 W transmitter is about 2 1/2 kilometres.
>>
>> 73
>> John Rabson
>> F5VLF
>> 58800 Cervon
>> France
>> JN17vg
>>
>>
>>
>>
>>
>>
>
>
>-- 
>
>http://g3xbm-qrp.blogspot.com/
>http://www.g3xbm.co.uk
>http://www.youtube.com/user/G3XBM
>G3XBM    GQRP 1678      ISWL G11088